To provide a modulated light beam comprising a plurality of optical wavelengths, prior art devices and methods commonly employ wavelength selective mirrors and filters to separate several selected wavelengths present in light from a source into component beams. The intensities of the component beams of selected wavelengths are separately modulated so as to control the individual intensity of each beam in accordance with, for example, signals representative of color information. The component beams are then recombined with additional optical mirrors or other such apparatus and deflected by well known scanning means or otherwise directed by mechanical optical devices to produce an information recording or display. The recordings and displays formed frequently suffer misregistration of the plurality of component beams due to physical variations in the many optical mirrors and other mechanical elements required.
Prior art devices and methods for projection or printing photographic pictures frequently use negative or positive transparencies which are illuminated so as to project the images contained therein onto photosensitive paper. The photographic materials used should be carefully matched to each other in order to provide proper color balance, contrast and color separation in the pictures printed. Sometimes the paper is exposed from the face of a cathode ray tube. The low intensity light output from the phosphors in these tubes means relatively long exposure times are needed which results in a relatively slow printing process in comparison with the printing process of the instant invention.
In accordance with the present invention, there is provided an apparatus and method of acoustooptically producing a composite output beam comprising a plurality of diffracted collinear and component beams of selected wavelengths which are each independently intensity modulated. Light containing several wavelengths is brought to operably impinge upon an acoustooptic cell. Electrical signals of different fixed frequencies are generated which correspond in number to the plurality of wavelengths selected for the output beam. The amplitudes of these electrical signals are independently modulated in accordance with a source of color information such as a color transparency. The electrical signals are combined to form a composite signal which is applied to an electrical-to-acoustical transducer operatively attached to the cell such that acoustic waves are generated within the cell which correspond to the individual fixed frequencies present in the composite electrical signal. The acoustic waves in the cell cause the light impinging thereon to be diffracted in a plurality of spectrums containing the wavelengths present in the impinging light, the spectrums corresponding in number to the fixed frequency signals applied to the transducer. The frequencies of the electrical signals are chosen so as to produce a composite output beam comprising collinear diffracted component beams of selected wavelengths. The intensities of every component beam is modulated in accordance with the amplitude of the electrical signal responsible for that beam. Thus, there is produced a composite output beam comprising a plurality of intensity modulated component beams of selected wavelengths. The modulated output beam is scanned to record or display information. The impinging light can comprise a multiwavelength beam; two different wavelengths can be collinear and the third noncollinear to the two; or the light can comprise beams of different wavelengths all impinging at different angles on the face of the cell. The angles of impingement and electrical frequencies used are mutually dependent as will be explained hereinbelow.
Since in practicing the invention, a plurality of beams with mechanical optical elements are not separated and subsequently recombined, more light passes through the optical system of the invention than in prior art systems. This provides for greater exposure in less time of, for example, photographic material. The system of the invention virtually eliminates misregistration of the individual component output beams which is a problem in prior art systems due to variations in optical mirrors and other mechanical elements.
In accordance with one embodiment of the invention, improvements in image quality of photographic prints are realized by optically scanning photographic storage mediums point by point, electronically processing the color information contained therein, and then recording the result point by point onto photographic paper. This scanning process provides for image enhancement by electric correction of the color information which results in better and more consistent color prints, eliminating the need for as perfect as possible matching of photographic spectra sensitivity in order to produce high quality prints.
Too, in accordance with the invention, a laser light source comprising a single multiple-wavelength laser, a combination of single-wavelength and multiple-wavelength lasers or a plurality of single-wavelength lasers is utilized rather than the cathode ray tube of many prior art photographic printing scanning systems. This enables shorter exposure times because of the greater light intensity available from lasers. Therefore, the embodiment of the invention for printing pictures provides faster printing rates than had previously been possible.
One object of the present invention is to provide an apparatus and method for separately and independently modulating a plurality of wavelengths in light beams impinging upon an acoustooptic cell so as to produce an output beam comprising collinear diffracted beams of wavelengths selected from those present in the input beams.
Another object of the present invention is to provide an improved apparatus and method for color display and recording such as television and photographic color picture printing.
Yet another object of the present invention is to provide an improved television-to-film recording apparatus and method.
Still another object of the present invention is to provide an apparatus and method for photographic color printing wherein the color balance of the resultant print is manually or automatically controlled.
Yet another object of the present invention is to provide an apparatus and method for color picture recording and printing wherein color masking and contrast corrections are made while printing onto photographic paper from either positive or negative transparencies or reflection prints.
One advantage of the apparatus and method of the invention is that registration difficulties inherent in prior art devices are overcome.
Yet another advantage of the instant invention is that the apparatus and method thereof provide for higher speed color photographic printing with improved color balance control.
Still another advantage of the present invention is that the apparatus utilized in accordance therewith is less expensive than that of prior art devices.